NASA Studies Scaled-Up SpaceX Falcon, Merlin

SpaceX will respond to NASA’s heavy-lift launch vehicle study with concepts that can carry 150 tons to orbit and cost no more than $300 million per launch.

Outlining SpaceX’s approach to the contract—one of 13 trade-study awards made by NASA in early November to look at innovative launch vehicle concepts and propulsion technologies—CEO Elon Musk says only plans that embrace economic, political and technical solutions will work.

“The physics is the easiest problem, but the economics and politics are quite pernicious. Any attempt at a solution that doesn’t try to satisfy those three constituencies—forget it,” says Musk, who refers to the study as super-heavy lift to distinguish it from Delta IV Heavy- and Falcon 9 Heavy-class launchers. “We’ll propose several things: One is to minimize development time and cost and make sure most importantly the operational cost and fixed cost of a super-heavy lift is low. Otherwise, cancellation is a certainty in the long term,” he says, referring to the inevitable budgetary pressure all programs will see in the face of the rising U.S. national deficit.

“When you look at all the sacred cows that will be slaughtered in an attempt to get that under control, then any super-heavy-lift program that is taking a long time is gone. Even if it’s done very well, then at best there’s a 50% chance of its not getting cut, or funded through flight. Termination is a certainty,” he adds.

Fast-track development, multi-use and low cost

are key, says Musk. “The development timeframe is on the order of five years and would come to fruition before [President Barack] Obama’s likely second term ends. It has got to fit within a NASA budget that fits in 2008 levels, and it’s got to have operational costs when functioning that is as close to zero as you can make it. That latter point demands that whatever components are in use for super-heavy lift must be in use for launching other satellites for say, geostationary commercial and government customers. If not, then the likelihood of success in my opinion is zero.”

Several approaches are being considered, including a super-heavy vehicle combining three Falcon 9 Heavy cores for a combined total of 27 main engines. However, a less costly option could include a launcher using scaled-up Merlin engines and a Falcon 9 first stage. “You could distill it down to one Falcon 9 Heavy and maybe one larger diameter core around 20 ft., and maybe three engines on that with thrust-to-weight ratios of 5:1 and make it a scaled-up Merlin and a scale-up of a Falcon 9 first stage to create that core. The only uncertainty you’re dealing with is scaling up,” says Musk.

In terms of the size of the scaled-up Merlin, he says: “We’re leaning at around 1.7 million lb. thrust, although at one point we looked at what if we went to 3.5 million lb. thrust. That does sound insane, I know, but the space shuttle solid rocket boosters are around 3 million.” With the baseline Merlin, which is throttle-able to 60%, SpaceX believes a version that could throttle down to around 1 million lb. could potentially equip vehicles such as the Atlas V as well as replace engines on Falcon 9. “Falcon 9 would just become Falcon, and Falcon 9 Heavy would just become Falcon Heavy,” says Musk.

“The cores combine to create a roughly 10-million-lb. liftoff mass. We will need something in that order. You basically combine three first stages to create your super-heavy. You can get a semi-free stage by cross-feeding from the outer cores, and you burn all the engines but only drain from outer tanks. So when side boosters separate, you have a full center core.” With a fully fueled center core, SpaceX believes this arrangement could allow the use of an unchanged Falcon 9 upper stage. “That way you get a three-stage super-heavy-lift vehicle, and all you’ve done is scale up the Merlin and Falcon 9 first stage. You essentially get a second stage for free,” says Musk.

Under SpaceX’s proposal, NASA would have overall systems oversight, and integration would be driven by Marshall Space Flight Center. “That would be a good way to go,” says Musk, who adds that “the only logical place” for final vehicle assembly remains Kennedy Space Center. “When you build a vehicle that big, it minimizes logistics; you can re-use the space shuttle pads and conceivably even make the tanks at Michoud [the current external tank facility in Huntsville, Ala.].

Based on a roughly evenly split $10 billion budget for heavy lift, with half for the boost stage and half for the upper stage, “we’re confident we could get a fully operational vehicle to the pad for $2.5 billion—and not only that, I will personally guarantee it,” Musk says. In addition, the final product would be a fully accounted cost per flight of $300 million, he asserts. “I’ll also guarantee that,” he adds, though he cautions this does not include a potential upper-stage upgrade.